The present invention relates to a network system, and more particularly, the present invention relates to technology for performing packet delivery through the gateway connected to the wide-area network.
Along with the trend of high-speed processing in the wider area, application field of the information communication network has been expanding. Generally, the system is established in a geographically limited place. Meanwhile, a large-scale network system via the wide area network has been envisioned. For example, a cloud service for social infrastructure is thought to be a typical system using the aforementioned information communication network for monitoring based on the information concerning regional events such as environment, weather, disaster prevention and crime prevention so as to provide appropriate information and services based on monitored results.
In order to realize the cloud service, it has been thought that use of information on the sensor installed on site shared by a plurality of cloud services ensures cost reduction compared with individual provision of sensors for the respective purposes of the service. Compared with reception/transmission of the predetermined information between the cloud services, transfer of the sensor information to the appropriate cloud service by the network system through autonomous interpretation of such information is thought to allow the sensor information to be shared without using particular means for the application.
Actually, IP multicast communication, and L7 packet communication as disclosed in JP-A-2005-159430 have been employed for transferring the packet that includes the sensor information through autonomous interpretation to a plurality of destinations. When sharing the information among the cloud services by transferring the packet to a plurality of destinations, it is necessary to prevent increase in both communication traffic volume and information processing load on the network.
For example, JP-A-2005-159430 discloses the method of improving delivery efficiency by allowing the gateway to identify the path of the network system using the identifier identified by the application layer, and reducing the network load upon data delivery for the purpose of reducing the load on the network when delivering large volumes of data to a plurality of places simultaneously.
In view of the problem of increase in the communication traffic volume on the network, JP-A-2011-198284 discloses the method of suppressing transmission of the content performed by the node device if it is judged that data volume exceeds a predetermined value for the purpose of preventing excessive transmission of the content from the predetermined network to the other network.
WO2011/102317 discloses the method of reducing the communication traffic volume by performing data compression and filtering in accordance with data severity and the band status of the network provided by the network connection unit as a result of analysis of the content of incoming data to the network connection unit.